Railway signaling system



March 19, 1929. R. M. GlLsON RAILWAY VSIGNLING SYSTEM Filed April 17,192

' sections C-D, D-E, etc.

the arrow.

Patented Mar. 19, 1929.

ROBERT M. erLsoN, or PITTSBURGH, PENNsYnVANrA, Assrenon To'. Tian UnionSWITCH a steam. COMPANY, or sWrssvaLE, PENNSYLVANIA, ir coarse-africa orPENNSYLVANIA.

v RAILWAY SIGNALING SYSTEM.

appiaaaonaieaapra17,1928, serial no. 270,59?.

My invention relates to railway signaling systems, and particularly tosystems lof the type involving polarized line circuits for the controlof three-indication signals.

' I will .describe one form of system einbodying my invention, and willthen point out the novel features thereof in a claim.

` The accompanying drawing is a diagrammatic view showing one form ofsystem embodying Vmy invention.,

Referring to the drawing, the reference characters l and l@ designatethe track rails of a railway track along which traic nor-A mally movesin the direction indicated by l These rails are divided by insulatedjoints 2 to form a pluralityof track Each section is provided with atrack circuit comprising a source of current 12 connected across therails at the exit end of the section, and a track relay connected acrossthe rails at the entrance end of the section, each track relay beingdesignated by the referencecharacter T with a suitable exponentcorresponding to the location. Y i

"Associated with each track sectionvis -a polarized line relaydesignated by the reference character L with an exponent correspondingto theflocation, and also .associated with each track section is aslow-releasing relay designated by the reference character A with anVexponent corresponding to the location. The line relay L for eachsection is controlled by the track relay for the same section and bypole-changing contacts on the slow-releasing.relay A for the sectionnext iin advance. For example, tbecireuit for lineV relay LC is fromterminal B of a 'suitable source of current, through 1 front Contact 4-of traekrelay TD, front point'of contact Sfof relay AD, frontcontaet 3of track relayTD,` 'winding ofl relay'LD, and front point of Contact 9of relay AD, to terminal O of the same sourceof current. The currentwhich is then supplied tov relayLC is of what l will term normalpolarity, so hat relay LD is then energized in the normal direction,wherein its normal contact 6 6@ is closed. When relay AD is open, buttrack relay TC is closed, the circuit for relay LC is from terminal B,through the back pointv of contact- 9 of relay AD, winding of relay LC,contact 3 of track relay TD, and theback e across contact 4.

includes merely the back point enters section C-eD. This trainopenstra.;

point ofcontact 8 of relay ADto terminal The current'then supplied torelayLC is of reverse polarity, so that the reverse vcontact (i--Gb ofthis relay -is closed. n It. will be noted that the eircuitglasttracedfor rel ayLD does not include the front contact 4t of track relayTD. The reason for this will be 'explained hereinafter, as 'well as thereason for the resistance -10 which .is connected Each relay A isprovided with a circuit which includes frontcontact 5 of the associ-l-ated line relay L, which circuit will `beiobvious from the drawing. KIt follows, that each relay A is energizedwhenever the vas-l sociatedrelay L is cle-energized.

Each traeksection is provided `with a'sig nal designatedby the referencecharacterxS with an exponent corresponding to the loca p tion. Each ofthese signals comprises a pre-- ceed lamp G, a Ycaution lamp Y,and avstop lamp R. Referring to signal SD, for ei;- ample, .the lcircuit forthe'procecd lamp (il is from terminal B, throughfront point of contact 7of the slow'releasing relay AD, nor'- mal contactA 6 6a kof relay LC,and lamp G to terminal O. Theeircuit for the caution lamp includes frontpoint of-centact '7 of relay'ACand thefrerverse'contact v(SK-(3" ofrclay LC. The circuit for the stop lamp 'R of contact 7 of relay AC.

The operation ofthe system Ais as follows: .Vf

When rthe parts are not intluenced by the presencev of trains, eachrelay L is ener-"' gized V'in Vthe normal direction, so .that allsignals S yindicate proceed.l I vwill new sume that a train' I'novingltoward the r C relay TC, lthereby denergizing relay L, which in turndenergizes relay AC, with the result that signalV Sechanges tothe stoplindication. As the train enters section'l-E, it deenergizes relays TD,LD and AD, so that signal SD. changes to the stop indication.

The pole-changingcontacts Sand 9 of relay AD are now reversed, so thatas. soon as track relay TC becomesenergized, relay LC will becomeenergized in the reverse direction, with the result that signal SD' willchangeto the caution indication? After the 65* train leaves section D-E,relays LD and AD Will become energized, so that-'relay LC will theproceed lamp G of signal SD.

then be energized in the normal direction,

and signal SD will again give the proceed indication. l v Q Theforegoing explanation of the opera tion of thesystein contains nomention ofv the track relay contacts 4. The reason for tliesecontacts,is as follows: Assuming that the circuit for relay LC does not includecontact 4 of track relay TD, then when a light engine passes point D athigh speed, track relay TC might become closed before the front contactsvof relay AD become opened.'Y Relay LC would then be energized in the.normal direction for a brief interval of time, with the result thatproceed l'anip G of' signal SD might be momentarily lighted, so thatthis signal would 'momentarily give the proceedindication. As soon assuch light engine enters section D-E, however, Contact 4 of track relayTD will open before contact 3 of track relay TC will close, with theresult that the normal circuit for relay LD is held open during-theinterval between the opening of relay TD and the opening of tliefrontcontacts of slowr -ileas-4 l-E from the venitv end, or if a switch inrthis section shouldlie opened., the opening of Contact 4 of relay TDwould open the normal circuit for relay LD before Vthe reverse circuitwould become closed attlie back contacts of relay AD, with the resultvthat relay Y LC would be: cle-energized, and the interval during''which this relayy is Lie-energized might be vsufficient to-'permit thecontacts of relay AD to release, with the result that .signal SD might*momentarily vgive a stop indication before changing to the cautionindication. To avoid this possibility, l have ,connected al resistancel0 across the contact 4 of each track relay, and the parts aresoadjusted that when line relay LC, 'for eX- ample, is closed, it willremain closed withV contact 4 open, provided, of course, that thecircuit for relay LC is closed at all other points. If relay LD 'isopen, however, v it will notV close in' resp-onse tothe current which itreceives through the resistance 10 when contact 4 is open. In otherwords, considering the normal circuit only relay LC, the parts are 'soadjusted that the current received by relay LC when contact 4 is open,is greater than the releasevalue of this relay but less than the pick-upvalue,

'wliereas, when contact 4 is closed the cur- Vrent received by relay LCis. greater than its pick-up value. Assuming now thata train backs intosection D--E, contact 4 of track relay TD will open, but sufficientcurrent will be supplied yto relay LD through resistance-10 to keep thisrelay energized, Awith the result that no vchange will occur in so fai'as relay LC is concerned until relay AD releases, whereupon, relay LCwill become energized in the reverse direction and signal SD will changefrom the proceed indication to the caution indication.v

Although l have herein shown and described only oiie form of systemembodying my iiivention,.it is understood that various changes and.modifications may be made therein within the scope ofthe appended claimwithout departing from the spirit and scope of my invention.

Having thus described niy invention, what l claim is:

ln combination, a strctch'of railway track divided into sections, atrack circuit including a track relay foreach section, a polare izedline relay for each section, Ya slow-releasing relay for each` sectioncontrolled bythe associated line relay, a cii'cuiti'for each line relay-including a front contact of 'the track relay for the associatedysection and pole changing contacts of theslowfor releasing relay forthe section -neXtiin advance, each line relay vcircuit including avfront contact of the track relay forthe section next in advance'whichVcontact is interposed between the source ofl current and one ofthe polechangingrcontacts in such circuit', each line relay Vcircuit alsoVincluding a resistance kconnected acrossthe last-mentioned track relaycontact, the parts of each line rclayfcircuit being so proportioned,that when the vlast-mentioned trackl relay Contact is open and thecircuit is otherwise closed, the line relay will remain'V closed if itis alread f closed but will not close if it is open, and signals for thesec` tions controlled by said line relays' and slow-releasing relays. IIn testimony whereof I affix my signature,

' ROBERT M. GILSON.

